A conventional driver of a speaker is operated by causing a voice coil of the speaker to vibrate, and move a cone of the speaker to reproduce sound pressure waves to allow a user to hear the sound. In order to achieve a better effect, the driver is mounted in a cabinet for preventing acoustic short circuit by separating a front and rear sound field of the driver.
During the vibration of the voice coil, if the voice coil moves forward, the density of the air in front of the driver is increased, and air density behind the driver is reduced. If there is no block therebetween, the air with greater density moves toward the air with less density, and this is called acoustic short circuit. Acoustic short circuit relates to the frequency, in particular appears in low frequencies. Therefore, a well-designed cabinet can improve the effect of low frequencies.
Referring to FIG. 1, there are two kinds of speaker boxes differentiated by the structures therein. One is enclosure speaker, and the other is ported speaker. The ported speaker can produce much lower frequencies than the enclosure speaker. Typical ported speaker has an opening 4 and a duct 6 for connecting the driver 2.
When a ported speaker operates, the air flows in the duct quickly. However, the opening of the ported speaker is usually of insufficient size, which causes frictional loss during operation and results in noise of the ported speaker.
Inasmuch as aforementioned, an omni-directional ported speaker is herein disclosed in the present invention to resolve the drawbacks of the prior art.